Multiple Energy Coordinated Control Based Onshore AC Fault Ride-Through Strategy for an All-DC Wind Power System

All-DC offshore wind farms (OWFs) have emerged as a promising alternative to conventional AC OWFs because of significantly reduced reactive power compensation requirements, eliminated synchronization stability issues, and improved operational efficiency. However, AC fault ride-through (FRT) for all-DC systems poses greater challenges, primarily due to the distinct topology and rapid fault propagation characteristic, which greatly hinders practical deployment. To address these challenges, this paper proposes a novel AC FRT strategy for the all-DC wind power system based on a multiple energy coordinated control (MECC) framework. It synergistically integrates capacitor energy control (CEC) of the high-voltage DC transmission (HVDC) system with adaptive power reduction control (APRC) of DC wind turbines (DCWTs). The MECC method facilitates fast and efficient elimination of surplus power by adaptively and sequentially coordinating four types of energy resources (namely, electrostatic energy in capacitors, kinetic energy of rotors, thermal energy from dissipative resistors, and wind energy captured by DCWTs) according to the severity of AC faults. During the AC FRT, the proposed MECC strategy effectively prevents DC overvoltage, improves energy utilization, and extends the uninterrupted operation time. Simulation results under typical AC fault conditions verify the effectiveness and superiority of the proposed MECC method compared with conventional methods.